Method for stabilizing a polymerized rosin and polymerized rosin ester



Patented Sept. 10, 1946 UNITED, STATES PATENT OFFICE METHOD FOR STABILIZING A POLYMER- r z l n ROSIN AND POLYMERIZED ROSIN Joseph N. Borglin, Wilmington, Del., assignor to Hercules Powder Company, Wilmington, Del., a

corporation of Delaware No Drawing. Application June 26, 1942, Serial No. 448,625

7 Claims. (01. zen-#103) The polymerization of rosin and rosin esters 2 melting point of 101 C'., was heated under a nitrogen atmosphere until a temperature of 286 C. was attained. At this point, one and one-half per cent of sulfur, based upon the weight of the 5 rosin, was added slowly, and the temperature was with sulfuric acid, boron fluoride, and other polyheld constant at 280 C. for three hours. After merization catalysts has been described in the art. this, the product was cooled. By means of this Such polymerized resins and rosin esters are procedure, the bromine number of the polymerhighly valuabl materials because they have inized rosin was reduced from 107 to 56 and the creased melting points in comparison with ordidrop melting point was increased. nary rosin and its esters. As a result, these poly- Example 2 merized materials have found wide use in the preparation of improved coating compositions .A samp of the Same polymerized es which dry to form much harder films than those ploye in Example 1 w heated under a r n obtainable from coating compositions prepared diOXide a p e o a te p of C-, from ordinary rosin and esters thereof. Moreat Which point e and One-half D t o 1 over, polymerized rosin and its esters possess a u based p e Weight Of t e polymerized lighter color and increased coltl'r. stability when e w added. The t ature of the reacsubjected to the action of light, heat,.etc., than tion mixture was held at 200 C. for three hours, rosin and rosin esters which have not been polyafterwhich t e p u was cooled- This D merized. Further important advantages and cedure reduced the bromine number of the polyuses of polymerized rosin and its esters have been e i ed rosin to 74. disclosed in the art.

Now, in accordance with this invention, a Emmpl? 3 method has been discovered for the further imp e f h p ly rlz d rosin employed in provement of the qualities of polymerized rosin Example 1 was heated under a carbon dioxlde and esters of polymerized rosin to provid a maatmosphere to a temperature of and two terial of increased stability. This novel method Per cent of l based upon the Welght of the comprises t t g a polymerized rosin or a polymerized rosin, was added. The temperature polymerized rosin ester with from about one to of the mlxtule Was-held i Y hours b t t per cent of ujlfur based upon the and then the reaction m xture was subJected to weight of the polymerized rosin or polymerized Vac1 1um to remove e ends- A Product, rosin este at a temperature between about 150 s a drop meltme point of and a and 350 C. under conditions adapted to effect bromme number was producedsubstantial dehydrogenation of the rosin or rosin Emmple 4 ester. The new product of this invention is a dehydrogenated polymerized rosin or polymerized The glycerol. ester of a 811115111 9301a polynger' rosin ester characterized by a bromine number ized msm, havmg a f meltmg pomt of 110 below about and by an increased melting point. was heated ,under mtrogen atmosphere to 280 It has been determined in accordance with this after which one and one'half per cent of invention that by dehydrogenatin polymeriz d 0 fur was added. 0 The temperature of the mixture rosin or polymerized rosin ester to provide a was held at 280 C. for three hours and the prodproduct with a bromine number below about 75 not was then By means of this proce' a material of substantially increased stability is the bmmine number 0f the ester was provided. duced from 82130 43.

Having thus indicated in a general way the Thus the Improved polymenzed rosin and Example 1 A rosin, polymerized with sulfuric acid while dissolved in benzene and having a drop *polymerized rosin esters are provided by contacting the polymerized rosin or polymerized rosin ester with sulfur under conditions adapted to effect substantial dehydrogenation of the material. The temperature range within which the dehydrogenation may be conducted may vary within wide limits. Reaction temperatures of from 200 to 280 C. were employed in the examples, but any temperature between about and about 350 0., and preferably from about 225 to about 3 280 0., will be found to be suitable. The amount of sulfur employed may also vary within wide limits. In the examples, the amount of elemental sulfur employed was one and one-half or two percent, based: upon the weight ofthe polymerized rosin or polymerized rosin ester. Generally, from about one to about ten and preferably from about one to about five per cent by weight of sulfur, based upon theweightv of the rosin or ester, is used as a dehydrogenating agent The reaction time which will be found to be most suitable will vary with the particular rosin or rosin ester being dehydrogenated, with thereaction temperature, with the degree ofd'ehydrogenation desired, and will also depend upon other obvious factors. not more than five hours is used.

The polymerized rosins which may be dehydroegenated in accordance with this invention may be those derived from any of. the various grades of wood or gum rosin. They may be produced fromisuch" rosins by polymerization according to any-of" the known methods, such as by treating with various catalysts. as sulfuric acid, organic substituted sulfuric acids, boron fluoride, metallic halides as stannic. chloride, zinc chloride, alumi nunr chloride, hydrogen fluoride, or by treatment of the rosins with a highvoltage, high frequency electrical discharge; or by treatment with an acid sludge formed by treatment of the rosin with sulfuric acid, such as isrdescribed in an application, Serial No. 328,864, filedApril 10, 1940, by Clell E. Tyler, now U. S. Patent No. 2,288,659. The poly merizedirosins whichmay. be dehydrogenated to produce the improved products of this invention willbe those. having adrop melting. pointfrom about 5 to about 100 C. above the melting point of the original jrosinused in the polymerization.

The polymerized.rosinesters which may be dehydrogenated' willinclude. polymerized monohydric alcohol esters and polymerized polyhydric alcohol esters of rosins which have been polymerized according to any of themethods mentioned in the precedingparagraph. Thus, they will include the methyl;,.ethyl, propy1, butyl, ethylene glycol, propylene. glycol, diethylene glycol, trimethylene glycol, glycerol, pentaerythritol, etc., esters of such polymerized rosins. Alternatively; the polymerized rosinesters maybe. prepared by-esterifying any of the: aforementioned alcohols with any wood or'g umrosin and then polymerizing the: ester with' any -of" the polymerization. catalysts mentioned in the preceding-paragraph, according to procedures well known. in the art. The poly merized rosin esters suitable for use in this invention are those having a drop melting point from about 5 to about 100C. above the melting pointfof the original rosin ester employed in the polymerization.

Before being subjected'to the dehydrogenation process described in this specification, the polymerizedi rosin or polymerized r0sin'ester may be subjected to a conventional heat treatment at a temperature from about 250 to about 350C. to effect a refining of the rosin ester. The methods for conducting such a heat treatmentare more fully disclosed in an application entitled Method of'refining polymerized rosin, Serial No. 371,991, filed December 2'7, 1940 by Raymond F. Schlaanstine and in an application, entitled Method of refining polymerized rosin esters, Serial No. 378,056, filed February 8, 1941 by Alfred L, Rummelsburg,

The dehydrogenation-process may be conducted; assh'own'in the-examples; by contacting the Generally, a reaction-period of polymerized rosin or polymerized rosin ester and the elemental sulfur as such. Alternatively, dehydrogenation may be effected with the polymerized rosin or ester thereof orthe sulfur,,or.both, dissolved in a suitable inert organic solvent, ,such as the parafiin hydrocarbons as hexane, V, M. & P. naphtha, etc., the aromatic hydrocarbons such as benzene, toluene, xylene, etc., the mixed aromaticalicyclic-hydrocarbonsias tetrahydronaphthalene, etc;, thealicyclic hydrocarbons as cyclohexane, decahydronaphtha'lene, etc., Solvesso No. 1, 2, 3, 4, etc. Dependinguponlthe reaction temperature and upon .the,vaporrpressure of the solvent employed the. dehydrogenation may be conducted at atmospheric or superatmospheric pressure, and thepolymerized rosin or polymerized rosin ester maybe dehydrogenated by a batch or continuous process; As shown in the examples, the method of this invention is preferably conducted under an. inert. atmosphere, suchasnitrogen or. carbon dioxide, in .ordento.pro.duce.products,of the.light est color.

AS shown in Examplev 3, the .productmayalso;

be improved by subjecting.the.polymerized rosin to .a .partiaLvacuum distillation at. the, end of the reactionperiod :in.order. to remove .thelight ends- Furtherimprovementmay also be obtained.by,.removing. the lightends through continued :Sparging, with.an-inert,gas,such as carbondioxide 0r-,nitrogen,. or. by combinationof tlie= sparging, and. vacuum distillation.

The polymerized. rosin and. polymerized. rosin, ester. prepared as: described herein are .highly useful and desirableproducts characterized.bygreat.

stability and highmelting point. Thus, these: polymerized products find importantluseincoating compositions;adhesives, paper sizes,.soaps, rubber compounds, etc., of increasedresistance to. oxidation anddeterioration through other causes What .I. claim. and. desirev to protect. by Letters.

Patentis:

1. The method of stabilizing, amaterial selected. from. the group consisting. of. polymerized rosin and. polymerizedrosin. esterswhichi com. prises.- contacting. the. material. with from. about.-

one to about. ten. per cent of sulfur, basediupon the weight. of. said material,- attae. temperature. between. about .150 and about 350 C. until the bromine numberof the material. has. become. reducedto. below aboutz without a..decr.ease-in' its. melting. point.

2t The. method. of. stabilizing;a -ma-terial selected. from: the: l'oupconsisting. of. polymerized; rosin. and; polymerized rosin. esters whichcomprises; contacting thematerial with from about'one-to aboutfive per. cent. of sulfur, based upon the; weight of said material, at-artemperature between: about 225" and about 280 C. until theibromine: number of the. materialhasbecomerreducedf to? below about 75 withouti-ai decrease in' its 'melt ing point;

3. Themethod of 'stabllizingrpolymerizedJrosin whioh'comprisesi contacting'the polymerized "rosin with from about one to about ten per cent of sulfur, based. upon the weightxof therosin', at

a temperature between about and'ab out 350" C. untilithe bromine" number of the polymeriz'ed rosin hasbecome reduced to below about '75" without a decrease in its' melting point:

4. The method" of stabilizing a polymerized rosin glycerol ester whichcomprises contacting the ester with from abonttone: to about ten per cent of sulfur, based upon the. weightof. the ester,.at a temperature. betweemabout 15.03 and. about 350"C'. until'the bromine number of the polymerized rosin ester has become reduced to below about '75 without a decrease in its melting point. i

5. The method of stabilizing a polymerized rosin pentaerythritol ester which comprises contacting the ester with from about one to about ten per cent of sulfur, based upon the weight 01 the ester, at a temperature between about 150 and about 350 C. until the bromine number of the polymerized rosin ester has become reduced to below about 75 without a decrease in its melting point.

6. A method of stabilizing polymerized rosin which comprises contacting the polymerized rosin with from about one to ten per cent of sulfur, based upon the weight of the rosin, at a temperature between about 200 C. and 350 C. 7. A method of stabilizing a material selected from the group consisting of polymerized rosin and polymerized rosin esters which comprises contacting the material with from about one to ten per cent of sulfur, based upon the weight 01 said material, at a temperature between about 150 C. and 350 C.

' JOSEPH N. BORGLIN. 

